media: zr364xx: fix memory leaks in probe()

media: zr364xx: fix memory leaks in probe()

[ Upstream commit ea354b6ddd6f09be29424f41fa75a3e637fea234 ]

Syzbot discovered that the probe error handling doesn't clean up the
resources allocated in zr364xx_board_init().  There are several
related bugs in this code so I have re-written the error handling.

1)  Introduce a new function zr364xx_board_uninit() which cleans up
    the resources in zr364xx_board_init().
2)  In zr364xx_board_init() if the call to zr364xx_start_readpipe()
    fails then release the "cam->buffer.frame[i].lpvbits" memory
    before returning.  This way every function either allocates
    everything successfully or it cleans up after itself.
3)  Re-write the probe function so that each failure path goto frees
    the most recent allocation.  That way we don't free anything
    before it has been allocated and we can also verify that
    everything is freed.
4)  Originally, in the probe function the "cam->v4l2_dev.release"
    pointer was set to "zr364xx_release" near the start but I moved
    that assignment to the end, after everything had succeeded.  The
    release function was never actually called during the probe cleanup
    process, but with this change I wanted to make it clear that we
    don't want to call zr364xx_release() until everything is
    allocated successfully.

Next I re-wrote the zr364xx_release() function.  Ideally this would
have been a simple matter of copy and pasting the cleanup code from
probe and adding an additional call to video_unregister_device().  But
there are a couple quirks to note.

1)  The probe function does not call videobuf_mmap_free() and I don't
    know where the videobuf_mmap is allocated.  I left the code as-is to
    avoid introducing a bug in code I don't understand.
2)  The zr364xx_board_uninit() has a call to zr364xx_stop_readpipe()
    which is a change from the original behavior with regards to
    unloading the driver.  Calling zr364xx_stop_readpipe() on a stopped
    pipe is not a problem so this is safe and is potentially a bugfix.

Reported-by: syzbot+b4d54814b339b5c6bbd4@syzkaller.appspotmail.com
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>